v1.0.0 — first stable release

Public API (src/Contracts/*) and DB schema frozen under SemVer (see VERSIONING.md).
Honest-core, fail-loud posture for the declared scope (AEAT Verifactu). Unsupported
cases are rejected with ValidationException, never emitted as wrong fiscal XML.
See CHANGELOG [1.0.0]. Closes AID-262.